The present invention relates to aircraft flight controls for lateral control and roll rate control of an aircraft, and more particularly to auxiliary flight control surfaces, or so-called flaperons, for aircraft.
An aerodynamic problem that has long plagued aviation concerns lateral control of aircraft during certain conditions of flight. In the lateral control of an aircraft during turn and roll maneuvers, for example, conventional ailerons or flaperons are employed, and generally are adequate for conventional aircraft employing relatively thick wings. However, the effectiveness of ailerons or flaperons on aircraft having relatively thin wings is severely reduced or impaired during transonic maneuvers. Moreover, it is well known that supersonic aircraft can suffer control reversal at transonic speeds, which can have an adverse effect on lateral control and rate of roll of the aircraft.
The use of conventional ailerons or flaperons on thin wing combat aircraft, furthermore, requires additional structural weight in the wings to obtain the rigidity necessary to achieve the required roll rate or time to bank angle.
A number of devices have been proposed to overcome the problem discussed above, some of which have been, and now are employed on aircraft; such as multiple and single spoilers, spoiler and aileron/flap combinations, etc., all of which impose penalties of a one kind or another on the overall efficiency of the wings during normal flight since it is not practicable to maintain aerodynamic smoothness or surface continuity on the wing surfaces with such devices, for normal flight.
In addition, such devices tend to be unduly complex, expensive, and frequently substantially reduce the structural strength of the wings. Also, the more complex devices are subject to malfunction or possible failure.
Contemporary military aircraft designed for sustained supersonic flight require wings with ultra-thin sections that obviously limit the options available in the use of prior known auxiliary aircraft control devices.